Polymeric microspheres (i.e., microspheres formed at least in part from a polymer) are used in medical and industrial areas. These microspheres may be used as drug delivery agents, tissue bulking agents, tissue engineering agents, and embolization agents, for example. Accordingly, there are a variety of methods directed towards preparing polymeric microspheres. Typical methods include dispersion polymerization of the monomer, potentiometric dispersion of dissolved polymer within an emulsifying solution followed by solvent evaporation, electrostatically controlled extrusion, and injection of dissolved polymer into an emulsifying solution through a porous membrane followed by solvent evaporation.
Additional methods of preparing polymeric microspheres include vibratory excitation of a laminar jet of monomeric material flowing in a continuous liquid medium containing a suitable suspending agent, irradiation of slowly thawing frozen monomer drops, emulsification and evaporation, emulsification and evaporation using a high shear air flow, and continuous injection of dissolved polymer into a flowing non-solvent through a needle oriented in parallel to the direction of flow of the non-solvent.